code: def main():
      parser = argparse.ArgumentParser(
          description="Launch a distributed job"
      )
      parser.add_argument(
          "--ssh_port", type=int, default=22, help="SSH Port."
      )
      parser.add_argument(
          "--ssh_username",
          default="",
          help="Optional. When issuing commands (via ssh) to cluster, use the provided username in the ssh cmd. "
          "Example: If you provide --ssh_username=bob, then the ssh command will be like: 'ssh bob@1.2.3.4 CMD' "
          "instead of 'ssh 1.2.3.4 CMD'",
      )
      parser.add_argument(
          "--workspace",
          type=str,
          help="Path of user directory of distributed tasks. \
                          This is used to specify a destination location where \
                          the contents of current directory will be rsyncd",
      )
      parser.add_argument(
          "--num_trainers",
          type=int,
          help="The number of trainer processes per machine",
      )
      parser.add_argument(
          "--num_omp_threads",
          type=int,
          help="The number of OMP threads per trainer",
      )
      parser.add_argument(
          "--num_samplers",
          type=int,
          default=0,
          help="The number of sampler processes per trainer process",
      )
      parser.add_argument(
          "--num_servers",
          type=int,
          help="The number of server processes per machine",
      )
      parser.add_argument(
          "--part_config",
          type=str,
          help="The file (in workspace) of the partition config",
      )
      parser.add_argument(
          "--ip_config",
          type=str,
          help="The file (in workspace) of IP configuration for server processes",
      )
      parser.add_argument(
          "--num_server_threads",
          type=int,
          default=1,
          help="The number of OMP threads in the server process. \
                          It should be small if server processes and trainer processes run on \
                          the same machine. By default, it is 1.",
      )
      parser.add_argument(
          "--graph_format",
          type=str,
          default="csc",
          help='The format of the graph structure of each partition. \
                          The allowed formats are csr, csc and coo. A user can specify multiple \
                          formats, separated by ",". For example, the graph format is "csr,csc".',
      )
      parser.add_argument(
          "--extra_envs",
          nargs="+",
          type=str,
          default=[],
          help="Extra environment parameters need to be set. For example, \
                          you can set the LD_LIBRARY_PATH and NCCL_DEBUG by adding: \
                          --extra_envs LD_LIBRARY_PATH=/usr/local/cuda/lib64:$LD_LIBRARY_PATH NCCL_DEBUG=INFO ",
      )
      args, udf_command = parser.parse_known_args()
      assert len(udf_command) == 1, "Please provide user command line."
      assert (
          args.num_trainers is not None and args.num_trainers > 0
      ), "--num_trainers must be a positive number."
      assert (
          args.num_samplers is not None and args.num_samplers >= 0
      ), "--num_samplers must be a non-negative number."
      assert (
          args.num_servers is not None and args.num_servers > 0
      ), "--num_servers must be a positive number."
      assert (
          args.num_server_threads > 0
      ), "--num_server_threads must be a positive number."
      assert (
          args.workspace is not None
      ), "A user has to specify a workspace with --workspace."
      assert (
          args.part_config is not None
      ), "A user has to specify a partition configuration file with --part_config."
      assert (
          args.ip_config is not None
      ), "A user has to specify an IP configuration file with --ip_config."
      if args.num_omp_threads is None:
          # Here we assume all machines have the same number of CPU cores as the machine
          # where the launch script runs.
          args.num_omp_threads = max(
              multiprocessing.cpu_count() // 2 // args.num_trainers, 1
          )
          print(
              "The number of OMP threads per trainer is set to",
              args.num_omp_threads,
          )
  
      udf_command = str(udf_command[0])
      if "python" not in udf_command:
          raise RuntimeError(
              "DGL launching script can only support Python executable file."
          )
      submit_jobs(args, udf_command)
  
imports: import argparse
  import json
  import logging
  import multiprocessing
  import os
  import queue
  import re
  import signal
  import subprocess
  import sys
  import time
  from functools import partial
  from threading import Thread
  from typing import Optional
label_desc: Use image node_id 15 for calling a global function with example usage: main() without return types